:During the initial three years of the Georgetown CERT (GUCERT) the program studied adverse drug interactions (ADIs), particularly those that result in drug-induced cardiac arrhythmias for which women are at increased risk. These original studies have identified new potentially lethal interactions and fostered awareness of ADIs across a wide array of drug classes. Healthcare providers have been unable to prevent ADIs in practice and we have found that curricula of medical schools and medicine residencies contain little information to prepare them to prescribe in ways that avoids harm from ADIs. GUCERT has developed curricula and aides to instruct providers on the range of potential ADIs, and is currently implementing and evaluating these educational programs. With the move to the Arizona Health Sciences Center, the new AzCERT continues the study of drug-drug interactions that result in arrhythmias. The web-based registry, www.QTdrugs.org, continues as the mechanism for initiating these studies. A major finding with life-saving potential is the observation that methadone can induce lethal ventricular arrhythmias. Mechanistic studies performed by AzCERT investigators now make it possible to test preventive measures. Newly proposed projects in this application will include a clinical study of the predictors of methadone-induced QT prolongation. The transition of the GUCERT to the AzCERT creates opportunities to expand the definition and scope of our research and convey this knowledge to healthcare providers and consumers in the multicultural context of the southwest. Our knowledge of the potential contributing factors for ADIs is expanding dramatically and this poses a substantial challenge for all healthcare providers. Our experience during the initial three years has shown that drug interactions must be approached on multiple fronts. We now fully recognize that drug interactions can occur due to systemic failures in which consumers and multiple providers are independently managing therapeutics. Substitution of prescribed drugs, addition of non-prescription, herbal or neutraceutical therapies, and modification of dosing regimens by patients are common. The risk of adverse outcomes grows when providers and consumers do not openly communicate and share in the management of therapies. AzCERT will employ laboratory, clinical and health services research using our broader systemic definition of drug interactions. The entire healthcare delivery system will be examined for weaknesses and potential improvements that are designed to prevent drug-drug and drug-herbal ADIs. Of equal importance, AzCERT will address the provider-consumer dialogue and develop health communication models to minimize risks from these more broadly defined ADIs.